Bitumen is a heavy type of crude oil that may be found in naturally occurring geological materials such as oil sands, black shales, coal formations, and weathered hydrocarbon formations contained in sandstones and carbonates. Some bitumen may be described as flammable brown or black mixtures or oil-like hydrocarbons derived naturally or by distillation from petroleum. Bitumen can be in the form of anywhere from a viscous oil to a brittle solid, including asphalt, oils, and natural mineral waxes. Substances containing bitumen are often referred to as bituminous, e.g., bituminous coal, bituminous oil, or bituminous pitch. At room temperature, the flowability of some bitumen is much like cold molasses. Bitumen may be processed to yield oil and other commercially useful products, primarily by cracking the bitumen into lighter hydrocarbon material.
As noted above, oil sands represent one of the well known sources of bitumen. Oil sands typically include bitumen, water and mineral solids. The mineral solids typically include inorganic solids such as coal, sand, and clay. Oil sand deposits are found in many parts of the world, including North America. One of the largest oil sands deposits is in the Athabasca region of Alberta, Canada. In the Athabasca region, the oil sands formation can be found at the surface, although it may also be buried two thousand feet below the surface overburden or more. Oil sands deposits are measured in barrels equivalent of oil. It is estimated that the Athabasca oil sands deposit contains the equivalent of about 1.7 to 2.3 trillion barrels of oil. Global oil sands deposits have been estimated to contain up to 4 trillion barrels of oil. By way of comparison, the proven worldwide oil reserves are estimated to be about 1.3 trillion barrels.
The bitumen content of oil sands can vary widely. In some oil sands, the bitumen content ranges from approximately 3 wt % to 21 wt %, with a typical content of approximately 12 wt %. Accordingly, an initial step in deriving oil and other commercially useful products from bitumen typically requires extracting bitumen from the naturally occurring geological material so that the bitumen may then be upgraded. In the case of oil sands, this may include separating the bitumen from the mineral solids and other components of oil sands.